I am sure that the stock injectors will have the capacity to run at a higher Duty Cycle, which is what will be needed to keep the AFR's under control for the bigger 128cu/in displacement. The ECU would need the appropriate setup done on a dyno and the operator will be able to say whether it's within the parameters needed for safe and performant motoring. If the stock injectors cannot spit fast enough, then the next size up will be required.